Piping failure
on the right abutment of Fontenelle Dam
resulting from seepage along ungrouted valley-side joints.

Soil mechanics
pioneers Karl Terzaghi and Arthur Casagrande spent much of their careers espousing
the potential pitfalls of hydraulic piping through dam
foundations. Terzaghi maintained that grout curtains should never be assumed
to be 100% effective. Casagrande asserted that no less than three rows
of
grout curtains should be employed beneath dams, with proper testing of the grout
take. Fontenelle Dam was constructed by the U.S. Bureau of Reclamation
on the Green River in Wyoming. During its initial filling in 1965 it suffered
a near catastrophic failure via hydraulic piping through the right abutment,
the
same failure mechanism that doomed Teton Dam 11 years later.

Ririe Dam was
built by the U.S. Corps of Engineers on near identical geology in the
next adjacent watershed to Teton Dam, at the same time Teton was constructed.
It
has never experienced the seepage problems that caused Teton Dam's untimely
demise. Find out why in the presentation "Could a Safe Dam
Have Been Constructed
At the Teton Dam Site?"